The IEEE 802.21 group includes mechanisms and procedures that aid in the execution and management of inter-system handovers. In particular, IEEE 802.21 defines three main services that can be accessed by mobility management (MM) applications in order to aid in the management of handover operations and system discovery and system selection. Among these services are event service (ES), information service (IS) and command service (CS). All these services share an important characteristic in that they are delivered using a common uniform interface with respect to prospective users, regardless of the underlying access technologies that support the communication with respect to the core network.
The delivery of event services and the generation of commands is typically determined by which event is be triggered based on the prevailing characteristics of the underlying technology. These underlying technologies may be 3GPP, 3GPP2 and IEEE-based wireless local area network (WLAN), (e.g., IEEE 802.11 or 802.16).
The IEEE 802.21 specification outlines various triggers and commands that are sent to and received from upper layers. However, the IEEE 802.21 specification does not describe how these events and commands are triggered and generated. There are no procedures or functionality to generate triggers toward upper layers, based on information provided by the 3GPP or 3GPP2 underlying layers. In particular, IEEE 802.21 does not describe how events and commands are triggered and generated when the underlying physical resources are based on 3GPP or 3GPP2 technology. Therefore, it is desirable to provide a method for generating these triggers.